Effect of nitrogen and sulfur on yield and yield components of sesame (Sesamum indicum L.) in calcareous soil

The study was carried out on sesame in North West of Pakistan. The experiment was laid out in RCBD having 3 replications. Four N and three S rates were applied in two splits one at sowing and second split with first irrigation. No of pods plant and grain yield (kg ha) were affected significantly by N, S and control vs rest. No of grains pod and 1000-seeds weight were affected significantly affected by nitrogen not sulfur. Mean values for nitrogen exhibited that highest grain yield (799.4) were obtained at 70 kg N ha ,while minimum grain yield (637) were recorded at 0 kg N ha. Mean values for sulfur revealed that highest grain yield (807.1) were recorded at 30 kg S ha, while minimum grain yield (628.6) were recorded at 10 kg S ha. Nitrogen and sulfur interaction showed that optimum grain yield (1030 kg ha) was noted at 70:30 kg N:S ha, while minimum grain yield (516.10 kg ha) was noted at 150:10 kg N:S ha. It is concluded that nitrogen and sulfur applied at the rate of 70:30 kg N:S ha perform better as compared to other treatment applied and thus recommended for attaining high yield.


Introduction
Sesame (Sesamum indicum L.) belongs to Pedaliaceae family.Till is its local name in Urdu and Punjabi, in Sindhi it is called tir, Konzala in Pashto and in Balochi it is called Kunjit.It is an oilseed crop.It is annual minor kharif short-day plant, and it flowers normally in 42-45 days [1].Its stem is erect and branched.The roots develop more profusely in sandy soil than in clay soil which imparts drought resistance to sesame.Flowers on short peduncles are borne singly in the axils of leaves of the upper portion of the stem and branches.The fruit of sesame is called capsule and it varies from 2.5 to 8.0 cm in length and 0.5 to 2.0 cm in diameter.Capsules starts maturing form bottom to top, allowing shattering of the lower ones by the time the uppermost capsules are mature.Seeds of sesame are small, ovate and are of two types due to its color differentiation, one is cream-colored and other type is black.Most people like Cream-colored seeds for use in sweet dishes and other foods.Sesame is grown in tropical zones as well as in temperate zones.In Asia and Africa it is cultivated from centuries.The world production of sesame seed was 3,976,968 tons in 2009 and the major production area was Asia (2,489,518  Seed oil contents were increased by N application except at the highest rate (90 kg N ha -1 ) which slowly reduced oil content compared with the control(zero) [7].Sulfur is also famous as one of the essential elements for plant growth particularly for oilseed crops.Sulfur is a constituent of three amino acids commonly found in plants such as cysteine and methionine, which are essential components of proteins.Sulfur gives pungency to oil as it forms di sulphide linkages and also increases oil content.Oilseed crops require more sulfur than cereals as their oil storage organs are mostly proteins, rich in S. Sulfur deficiency delay N metabolism in plants as well as synthesis of S-containing amino acids and thus exerts adverse effects on both seed and oil yield.Soil and climatic conditions of Pakistan are highly encouraging for sesame production.Among the various factors of crop production proper sowing dates, nitrogen levels, sulfur levels and improved sesame cultivars play a key role in enhancing its production.Keeping in view the above limitations this research was conducted to check out the impact of nitrogen and sulfur levels on the yield and yield components of sesame at the agro-climatic condition of Northwestern Pakistan.

Site description
The field experiment was studied at The Agronomy Research Farm, The University of Agriculture Peshawar, during kharif 2013.The experiment was laid out in RCBD with three replications.A subplot size of 2.7 m x 3 m was used.Each sub plot was consisted of 6 rows having 45 cm row-to-row distance.
Local black variety of sesame was sown on June 29, 2013.During the entire crop season four irrigations were applied and two time manual weeding was done.Phosphorus was applied at the recommended rate of 60 kg ha - 1 .Seed rate was kept 4 kg ha -1 and all other agronomic practices were carried out consistently for all the experimental units throughout the growing season.The crop was harvested on October 24, 2013.

Number of pods plant -1
Number of pods plant -1 were affected positively by different levels of nitrogen, sulfur, control vs. rest and their interaction (N x S).In (Table 1) mean values for nitrogen proved that more number of pods plant -1 (174.9) were recorded at 110 kg N ha - 1 while less number of pods plant -1 (138) were recorded at 0 kg N ha -1 .In case of sulfur (Table 3) more number of pods plant - 1 (196.1)were recorded at 30 kg S ha -1 , While less number of pods plant -1 (138) were recorded at 0 kg S ha -1 .In case of Interaction N×S (Table 4) more number of seeds pod -1 (220.7) were recorded at 70 kg N and 30 kg S ha -1 , while less number of seeds pod -1 (109.3) were recorded at 70 kg N and 10 kg S ha -1 .The number of pods were significantly influenced by application of N fertilizer [8].N fertilizer application at 75 and 112.5 kg N ha -1 did not differ significantly from each other but differ with 37.5 and 0 kg N ha -1 rates with higher values.The effect of different sulfur applications were statistically significant on number of capsules per plant [9].Capsules per plant were increased by each increment of nitrogen fertilizer [10].Application of sulfur at 40 kg ha -1 produced higher pods plant

Number of seeds pod -1
Number of seeds pod -1 were affected significantly by nitrogen and control vs. rest, while non-significantly affected by sulfur and the interaction of nitrogen and sulfur.In (Table 2) mean values for nitrogen mediated that more number of seeds pod -1 (73.9) were obtained at 150 kg N ha -1 ,while less number of seeds pod -1 (63) were attained at 0 kg N ha - 1 .In case of sulfur (Table 3) more number of seeds pod -1 (72.3) were achieved at 20 kg S ha -1 , while less number of seeds pod -1 (63) were recorded at control.In case of interaction (N×S) (Table 4) more number of seeds pod -1 (76.3) were recorded at 110 kg N and 30 kg S ha -1 , while less number of seeds pod -1 (68) were recorded at 30 kg N and 10 kg S ha -1 .The higher significance difference among nitrogen levels for number of seeds capsule -1 was recorded Data was subjected to analysis of variance (ANOVA) according to the methods described by Steel and Torrie (1980) and mean difference b/w treatments was compared by least significance difference at 5% level of probability.

Table 2 . Impact of Nitrogen on yield and yield components of sesame. N (kg ha -1 ) No of pods plant -1 No of seeds pod -1 1000 grains wt. (g) Grain yield(kg ha -1 )
significantly by control vs. rest, sulfur and interaction between nitrogen and sulfur.In (Table2) mean values for nitrogen showed